1. Field of the Invention
The present invention relates to a shed forming device in a weaving loom comprising a tilting retaining hook.
2. History of the Art
It is known that, in shed forming devices in a weaving loom, a system may be used for lifting each harness cord which is composed of two mobile hooks each fastened to the end of a funicular element which cooperates with a lifting beam associated with the harness cord. The two mobile hooks are lifted and lowered alternately by knives provided in the shed forming device, whilst elastic blades having a curved end, associated with an electromagnet, are urged into the upper part of each system in order to selectively retain the corresponding hook in high or top dead center position.
One of the ends of the blades in question must be embedded in a block, while its other curved end cooperates with the corresponding hook. The blades are made of spring steel so as to be elastic. It will be readily appreciated that such an arrangement is not reliable, as the spring blades are subjected to continual, very high-rate bending moments when controlling warp yarns of a high-speed weaving loom. These blades therefore break frequently, bringing about a shut down of the equipment, thus leading to an increase in production costs, without counting the actual costs of repair.
In addition, it will be appreciated that as the elastic blades are reduced in cross section due to wear the value of the flux which passes therethrough, will be correspondingly reduced, so that the power of each electro-magnet is reduced.
Finally, the blades are made of spring steel, such as a carbon steel, with the result that they may be detrimental to the correct operation of the system.